#首先检索某月作答个数大于等于3的用户,然后对于这些用户统计他们所有的试卷数据select tag,COUNT(tag) as tag_cnt from exam_record join examination_info using(exam_id) where uid in (select uid from exam_record where submit_time is not null group by uid,date_format(submit_time,'%y%m') having count(submit_time)>=3)group by tagorder by tag...